You are initialising your birthdaypeople array everytime in each iteration which is why the else block is never executed because for every j the birthdaypeople array is new and have false value. Take out the array declaration out of the for loop.
boolean[] birthdaypeople = new boolean[n];
for (int j = 0; j < n; j++) {
int birthday = (int) (Math.random() % n);
if (!birthdaypeople[birthday]) {
birthdaypeople[birthday] = true;
} else {
peopleindex[j + 1]++;
break;
}
}
solved Why the “break” in the loop doesn’t fuction [closed]